Composite die for nut machines



Sept. 18, 1951 J. H. FRIEDMAN 2,568,440

COMPOSITE DIE FOR NUT MACHINES Filed Sept. 9, 1948 INVEN TOR. JOHN H-H'P/EDMA N Rwy M A TTOENEYS Patented Sept. 18, 1951 COMPOSITE DIE FORNUT MACHINES John H, Friedman, Tiffin, Ohio, assignor to The NationalMachinery Company, Tiffin, Ohio, a

corporation of Ohio Application September 9, 1948, Serial No. 48,400

3 Claims.

This invention relates to dies for use in heading or upsetting machinesand particularly to a knock-out pin or the like, and from any flow ofthe metal with respect to a die surface during the forming operation.

The most suitable materials for the die surfaces subjected to metal floware the extremely hard tool materials, such as cemented carbide,hardened non-deforming tool steel, and the like. However, the highhardness of such materials is accompanied by limited ductility, so thatbreakage may occur within the elastic deformation of the metal of theframe or other die supporting part of the machine under the hydrostaticpressure of upsetting. Such materials are also costly and difiicult tomachine, so that it is not economical to make an entire die of extremelyhard material of suflicient cross-section to withstand the upsettingloads.

The principal object of the present invention is to reduce the cost ofupsetting operations by increasing the useful life of the dies,particularly dies subjected both to metal flow against a die surface andto hydrostatic upsetting pressures.

Other objects are to minimize the cost of the materials of the die andthe cost of the die sinkin or forming operations.

I have discovered that a composite die capable of withstanding the highcompressive forces applied thereto by the hydrostatic pressure of-upsetting and also capable of withstanding,

through a long period of service, the wear and erosion of metal flow,may be constructed of an inner portion of high hardness materialproviding a wear resistant face, and a portion of relatively toughmaterial receiving the principal upsetting forces which is maintainedunder initial compression so as to prevent breaking of the high hardnessportion by excessive stretchin or yielding of the remainder of the die.I have also discovered that such dies can be constructed 'with a minimummaterial cost and with a substantial saving in the cost of fabricatingthe die.

Examples of one-piece dies, and of the character of operations for whichboth one-piece dies and the composite die which forms the subject of thepresent application are used, are disclosed in my copending applicationsfor Method and Apparatus for Making Nuts, Serial No. 547,849, filedAugust 3, 1944, issued on February 20, 1951, as Patent Number 2,542,022,and for Machine for Making Nuts, Serial No. 663,569, filed April 19,1946, issued on February 20, 1951, as Patent Number 2,542,864.

The manner in which the principal objects of the invention are realized,and various other objects more or less ancillary in nature, will beapparent to those skilled in the art from the description herein of thepreferred embodiment of the invention which is illustrated in theappended drawings of which:

Fig. 1 i a longitudinal view, partly in axial section, of a compositedie;

Fig. 2 is an end view of the same; and

Fig. 3 is a detail, greatly enlarged.

The die disclosed herein is adapted for use in heading and upsettingmachines generally, and may relace previously known one-piece dies insuch machines; and it is therefore considered unnecessary to discloseherein the heading machine or such elements as punches, knockouts, andthe like used with the die. A full disclosure of such matters may befound in the abovementioned Friedman applications and in the patents toClouse, No. 2,026,823 and Prayer, No. 2,100,028. It is to be understoodthat the die of this invention is adapted for use in machines of varioustypes and is not restricted to use in the above-mentioned machines,which are cited purely as examples of environments in which theinvention may be used.

In the preferred embodiment, the composite die is composed of threeparts which may be identified as a die holder A, composed of material ofhigh ductility and toughness, such as a nickel-chromium die steel, a dieB, composed of relatively tougher material such as high speed toolsteel, and a die insert C composed of extra good wearing material, suchas cemented carbide, hardened non-deforming tool steel, or other goodmaterial. The die holder comprises a preferably cylindrical body drilledalong its axis to form a central bore II and bored out to a largerdiameter at the front of the die to form a recess I2 for the die B, thebore 12 being relieved at the inner end thereof as illustrated at l3.The

rear end of the die holder A is bored out to provide a cavity M whichmay accommodate a knockout pin and a bushing therefor (not shown). Thebore I2 is preferably a right circular cylinder and the shoulder l5 atthe bottom thereof is preferably radial. A notch IS in theT'outers'surfacea'of the the holder or other conventional arrangements may beprovided for cooperation with means for retaining the die holder in thedie block of the heading machine.-

The die B, in its external outline, is substantially a right circularcylinde'rfalthough' it may be, slightly tapered, and i's dimensioned:fora

press fit into the cavity |2- cf 'the-die"holder. The die B i formedwith an internal opening 2| which, as illustrated, is 'o f the formpL-ahexagonal prism extendin from one ens 'to the The hexahedral form-illus-" other of the die. trated is for a hexagon-Lnut, and, of course,the

flopenmgellfirnay bexofnother formsiorxother operations.

The die cavity 22 is defined by--. the s so'f the opening 2 l vandthe-face 3l of the nsertfl. q 1 i Et'hi's die inserttis formed :with ;-aprismatic exiteriereadaptedxto fit within the zprismatic opening Z I' ofthe *die, with a face 3| which may be -sconcaively dishedas.'illustrated, or of other forms dependingnpomthesfunction of the:die, and with a. central :bore :or passage 3.3 for a knockout pinor-tlie like.i altzis to be. noted that the .die insert c aoes n'o't.necessarilyabut: the die holder A since the bore ll may .be ofgreaterradius than 1 itheidie insert. .In this case it'heiinsert C,isl'balcked nip by atbushing .or the. like around thevknockout pin; Itwill :be :understood thatlin :use theentire die inc'luding :theinsert-is solidly backed up by the bed trame :of ithie-zmach-ine whichthe die is used: r I

The illustrated die ;is. arrangedto form a -"dis'hed orchamferedlfacelon the hexagonal :nut

- agonalhole 22 f :the dieaB, .the intersection of tlieEiiished face3-l':with :the hexagonal :outer-surface "oifthe insert :produces ithin,runsupported points -34 ait each 'cornerzof the insert. .In ordertoprevent these poi-nts irom being broken off during upsetting, it :isnecessary to zpreventzexces- 'sive outward yieldmg of the vdieul3'underqthe hy" ostatic pressure -of upsetting. At :the same "-tinief-the'die B-cannotbe .pre-aloaded rto such an --*extent to 'break off the apoints "34 during assembly or' when :the upsetting pressures arereli'eved and the blank is ej'ectedin use.

These problems are solved by the .present'ainvention by a properdistribution 0f :elastic' stresses in the parts of the diei Themouth'cof .the die cavity 22 :is preferably slightly :ch'amfered :as:.illustrated .Fig. .3, "which is ian"ienlarged view, 7 the. scale beingapproximatelyatwentyvtimes the scale-of Figs. '1 and 2.

. Asshown, the entrance portion of the .cavity '2 I ais'taperedxat 26 atanangle :of about 10 to the aicisof the dierand the junction of the:tapered ssm'fiaceflfi-with the-outer face of the die radiused -asindicate'dat 21. "This-constructionfacilitates "*the assembly .of thedie according :to thepresent finvention. w ln'th'e fabrication ofthedieassembly, :the sev- -eral-jparts are -sep'arately -machi'ne'd :orground,

after which the die insert C is assembled in the die B. The die insertis preferably dimensioned for a tapped fit Within the die. In a dieapproximately of the size and proportions illustrated in the drawings,the diameter across the flats of the die insert C may be approximatelythreethousandths of an inch greater than the diameter of ":theopening 21in the dies" relation the insert may be -driven' into the the ibyrelatively light tapping, without danger of scoring the die or damagingthe sharp edges 34 of the die insert. This assemblyof the insert in thedieputs the 'inseit'C'iind'er some compression, and the die B iunderequivalentdiension. Alternatively, the dimensions of the insert C maybe the same as, or slightly' smaller than, the corresponding dimenns t.hwreaine The size of the opening in the die will of course depend uponthe size of the nut or other article to be formed. The over-all diameterof the die iBl-isipreferably ofilthe=order. iof twicegtheidianreter 5::ofj-theldiewcavity. The greatest putsidediameter "end thereof may exceed:the rdiameteraotthe sopeningd-zaby .a-:lesserramountxorithe inner end"o'fithe idie' B maytbeaotherwiserformedto;facilitate driving the dieinto thei iopening L2; The die ;B carrying "the insert rafterbeinggaligned -with 113118 :opening lz may be :=for.ced :into ;theposition illustrated in Fig. 1 by apress-zor theilike." .Ihis

' nperationichanges :the :stress fin. the metal of the .rdieIBsfromiaistate :of lightttensiontoaa state .iofrelativelyheavycompression,-andaputmtheimetal ":.of the holder A :inz-tension. yA Epartrof :the force :is :transmitted' to theiinsert 1G,increasing .rthe

- .Lcompress'ion? in jrtherinsert sand the remainder :is

ztakenrby'isompressien-rof .the -:metal; of :,the diezB. .Thus the:amount :of. radial: yielding :of ;the walls :of .the :die .33 ;under:the hydrostatic, ,pressurerof .upsettingi-is reduced shy; .thepre:loading=of :the

.die tandzthe corners Mini :the .insert i-Glremain .firmlyisupportedibyfbhfdielB.

W-bile the :partsaof ;-;the die may .be constructed of various materialsto suit different'requirementslin' ruse 'Iiihave found 1 that the bestresults for the :.illustra:ted "rdieiare obtained by the- :die 'ihold'erTA for: a :material zsuch .as mickel chrome: die steel, ithe :die 5B iof;a high ,speedxtool 'steel and' rthe inseizt' C "of :ceinented .asarhide01 hardened non-deforming IUOQliFStGBl. suitable :materrialfor'lthetdieholder hasrsheen: fionnditorzbe SAE steel No. 3150 whichcontains.lahouti;l%;.tto l 5% nickel, 5.45% :to .15 zchroineiiand tocarbon. A' suitablefiinaterial aforiihe. die;B any :01" the .yariousLhigh speed .tool Stealigcpntungsten, .225 120'1'5%,{Ch11011'1fl,' andI.5 %,,ito 225% wanadiumc with or without .rother lalloyinjg 181B-umen'ts'; :A'suitabl'e"non-deforming gsteel for;.'the

. :insert LC; which :may'abeiusedtiniplace .of;ce mented i Tmssing'iofthe-idie Bintothglioldgr A fa clli- :tated by itheformationpf .;avery;;sli

.ithepnter ssurf-acewf th -die. In the rtratedltithe.taper-rof theidieis about ye J sandths of an inch, and the inner end is about one or twothousandths of an inch larger than the bore [2 of the die holder. Itwill b understood that the values of clearances stated herein are thosewhich are believed to be best for the die disclosed herein and thatvariations in the values might be desirable in accordanc with changes inthe size of the die.

The central passage 2! of the die has been described as prismatic.Preferably, the portion of this bore in which the die insert C is lodgedis without taper, but it may be of any desired crosssection such aspolygonal or circular, to accord with the cross-section of the diecavity 22. The outer portion of the passage 2|, which forms the diecavity 22 may be either straight or tapered, depending upon the desiredshape of the die cavity.

It will be seen that the composite die structure illustrated herein isvery simple to fabricate. The use of the insert C eliminates thedifficulty of machining the conical surface 3|. It is a relativelysimple matter to machine all the parts of the die as will be apparent,and the assembling of the several parts is a simple operation. No greatforce is required to mount the die insert in the die, and thus there isno likelihood of damaging these parts. In pressing the die into the dieholder, a greater force is required, but the ram may bear against theplane outer surface 2 8 of the die.

It should be noted that while pressing is regarded as the most practicalmethod of assembling the die, the desired relative loading effect of theseveral members depends upon the dimensions of the parts, and may besecured, for example, by a method of assembly utilizing differ entialheating of the members rather than by pressing them into place. Thecompression of the die and the die insert, which together form theactive part of the die, by the massive die holder reinforces these partsand decreases the possibility of failure of the die. The individualparts may be of different materials selected for economy and ease ofmachining as well as for the best mechanical characteristics. For thesereasons a stronger die may be produced than in the one-piececonstruction, and the materials for the composite die are lessexpensive.

Although preferred embodiments of the invention have been described inconsiderable detail, it is to be understood that various modificationsand rearrangements of the parts may be resorted to without departingfrom the scope of the invention as defined in the following claims.

What is claimed is:

1. In combination a steel heading die having a polygonal die cavityextending into said die from the front face thereof, a die insert havinga polygonal exterior surface similar to, but normally larger indimensions than, said die cavity positioned in said die cavity andspaced from the front face of said die, said insert being formed ofmaterial harder than said die and having a concave front face forming awall portion of said die cavity, the intersection of the polygonalexterior surface and the concave front face of said insert formingprojecting corner portions closely engaging and supported by the wallsof the die cavity of said die.

2. In combination a steel heading die having a polygonal die cavityextending into said die from the front face thereof, a die insert havinga polygonal exterior surface fitting closely in said die cavity andspaced from the front face of said die, said insert being formed ofmaterial harder than said die and having a concave front face forming awall portion of said die cavity, the intersection of the polygonalexterior surface and the concave front face of said insert formingprojecting corner portions closely engaging and supported by the wallsof the die cavity of said die, and a steel die holder having an openingextending into said holder from the front face thereof with an interiorsurface similar to, but normally smaller in dimensions than, theexterior surface of said die, said die being positioned in said opening.

3. A die assembly for upsetting and forging metal articles comprising adie body having a polygonal die cavity extending therein from the frontface thereof, a die insert having a polygonal exterior surface fittingclosely in said die cavity and spaced from the front face of said diebody, said insert having a concave front face forming a wall portion ofsaid die cavity, the intersection of the polygonal exterior surface and.the concave front face of said insert forming projecting corner portionsclosely engaging and supported by the walls of the die cavity of saiddie body, and a die holder having an opening extending into said holderfrom the front face thereof with an interior surface similar to, butnormally smaller in dimensions than, the exterior surface of said diebody, said die body being positioned in said opening.

JOHN H. FRIEDMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 329,801 Allerdice Nov. 3, 18851,395,217 Begot Oct. 25, 1921 1,896,674 Longwell 'Feb. 1, 1933 1,935,821Simons Nov. 21, 1933 2,044,986 Horton June 23, 1936 2,146,995 Simons -1Feb. 14, 1939 2,147,888 Gaines Feb. 21, 1939 2,164,750 Nadler July 4,1939 2,350,465 Keshian June 6, 1944

